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Studies on the Oscillating Characteristics of the Photodetachment Cross Section of H~- Near a Metal Surface

Author: HuangKaiYun
Tutor: WangDeHua
School: Lu Tung University
Course: Atomic and Molecular Physics
Keywords: Closed-orbit theory Photodetachment cross section Electric field Metal surface Metallic microcavities
CLC: O572.3
Type: Master's thesis
Year: 2011
Downloads: 13
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Abstract

Photodetachment of negative ions is a typical example of the interaction of light and matter, and is also an important way to understand the anion structure. As we all know, the photodetachment process extremely vulnerable to the impact of the external environment. Initially, the main research photodetachment of negative ions in the electric and magnetic fields. In recent years, with the rapid progress of the laser and vacuum technology, the adsorbate near the surface of light-induced electronic excitation behavior has aroused great interest, while the hydride in charge of monitoring adsorbate life and after scattering process can be used to transfer people anion photodetachment extended to near the surface. Closed-orbit theory is generally used to explain the light absorption of atoms in strong external fields and ion photodetachment has clear physical picture of a wide range of applications. This paper is the use of the theory, respectively, to study the electric field, elastic interface hydrogen negative ion photodetachment cross sections of hydrogen negative ions in the vicinity of the metal surface the photodetachment modulation and metallic microcavities. The theoretical results for the experimental study anion system photodetachment near the surface provide a certain reference value, has a very important significance for the understanding of the electron scattering in the surface as well as the further development photodetachment microscope optics. The following three aspects: 1. Study the impact of the size of the direction of the electric field and electric field strength in the vicinity of the metal surface of the hydride photodetachment cross section of the main contents of the thesis. According to the closed-orbit theory, gradually the positive direction of the electric field and the z-axis angle α 0 degrees, 180 degrees and any value stripped classical trajectory of the electron, deduced the photodetachment cross section formula. The results show that when the electric field along the z-axis positive direction as the electric field intensity increases, the light peeling of the oscillation amplitude of the cross section becomes large, and the oscillation frequency becomes small. When the electric field along the z-axis negative direction, due to the external electric power and mirror Coulomb force is contrary to the direction of the biasing force of the peeling electronic photodetachment cross oscillation structure becomes very complicated. When an electric field is very small, the light peeling sectional Approaching the case in the presence of only the metal surface;, light peeling section and in the free space as in the case when the electric field is increased to equal the electric force and the mirror Coulomb force; when an electric field is very large The photodetachment cross Approaching the case when only an electric field exists. Maintain the same strength of the electric field, changing only the direction of the electric field, the more angle α approaches 90 degrees, light peeling oscillation smaller cross section. 2 flexible interface hydride in the electric field near the metal surface photodetachment. Study found signing elastic interface after photodetached more intense cross section of the oscillation structure, interface cause depends on the size and direction of the external electric field caused reinforcing oscillation. Upright when the direction of the electric field, the interface to enhance shorten the cycle and the role of the amount of the closed orbit oscillation; straight down the direction of the electric field, the interface through an increase in the number of closed orbit or increase range of incident light energy to produce coherent effects strengthen oscillation. 3 photodetachment of hydrogen negative ions in metallic microcavities. Metal microcavity consists of two parallel metal surfaces, in theory, can produce an infinite number of image charges, so peel electronic suffered the mirror potential is very complex. Thus, in this part of the first stripping electrons suffered image potential approximation semiclassical analysis and optical stripping cross sections. The study showed that the photodetachment cross oscillation of the regulation can be performed by changing the distance between the cavity wall and the hydride of the micro-cavity. Meanwhile, in order to clearly reveal the relationship between the sectional photodetached oscillation and closed orbit, photodetached scale cross-section of the Fourier transform, each peak in the Fourier Transform with a closed orbit subscript The degree of the role corresponding to the amount, thereby indicating that the sectional photodetached oscillation along the closed track the spread of the electron wave and a reflected wave due to interference. The thesis is divided into five chapters. The first chapter is an introduction, mainly introduced from the general the anion photodetachment significance of the study, a review of the history of the development of the closed-orbit theory. Also of the anion photodetachment Research and selected topics as well as the main work. The second chapter the use of closed-orbit theory to study hydrogen negative ions in the electric field near the metal surface photodetachment focus on the size of the direction of the electric field and electric field strength of light stripping cross sections. Chapter flexible interface hydride in the electric field near the metal surface photodetachment focus on the analysis of the interface caused by the oscillation strengthen photodetachment cross section. Chapter photodetachment of hydrogen negative ions in metallic microcavities, and reveals the relationship between the oscillation structure with closed orbit in the photodetachment cross section. Chapter 5 gives the main conclusions of this paper and the prospect of future research work.

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